The present invention relates generally to the field of electrical connectors. More particularly, this invention relates to devices that provide electrical connection between the respective conductors on first and second adjacent substrates, such as printed circuit boards ("PC" boards).
The trend toward increased miniaturization and more compact packaging of components and assemblies in the electronics industry has led to the development of connectors for electrically connecting the respective conductors on adjacent substrates, such as the conductive traces on adjacent PC boards.
A particular application for such connector devices is for providing electrical connection between adjacent PC boards that are removably stacked relative to one another; that is, removably mounted in a closely adjacent parallel relationship. One typical type of connector for such an application employs resilient or compliant contact elements to provide the electrical connection between the respective conductive elements on the adjacent PC boards. Specific examples of this general type of connector are disclosed in the following U.S. Pat. Nos. 3,795,037--Luttmer; 4,199,209--Cherian et al.; 4,295,700--Sado; 4,505,529--Barkus; 4,511,196--Schuler et al.; 4,738,625--Burton et al.; 4,806,104--Cabourne; 4,813,129--Karnezos; 4,983,126--Busse et al; 4,998,886--Werner; 5,016,192--Chapin et al.; 5,069,627--Buck et al.; 5,139,427--Boyd et al.; 5,147,207--Mowry; 5,152,695--Grabbe et al.; 5,160,268--Hakamian; 5,173,055--Grabbe; and 5,228,861--Grabbe.
In designing PC board connectors, there are a number of important considerations. For example, to optimize space utilization, it is desirable to minimize the space between adjacent boards. Thus, the thickness or "profile" of the connector must be minimized. Also, since the trend is toward more ever smaller component sizes and increased density of the arrangement of the components and conductors on the boards, it is necessary to provide a denser arrangement of conductive contact elements in the connectors; that is, an increased number of contacts in a given area. Often, this means decreasing the size of the contact elements themselves. Such downsizing of the contact elements, however, frequently degrades their durability and useful lifetimes, due to decreased structural strength. Thus, the design criteria of minimizing size and maintaining durability typically operate at cross purposes, resulting in the compromising of both criteria.
Furthermore, there will be often be slight variations in the nominal spacing between adjacent PC boards, thereby requiring the contact elements to provide positive electrical contact regardless of such variations. To do this, the contact elements must have a sufficient degree of deflection or travel to bridge inter-board gaps of varying distances. One solution to this problem is to provide a structure in which the connector has some freedom to move or "float" between the boards, as disclosed in U.S. Pat. No. 5,160,268--Hakamian. One drawback to this approach, however, is a relatively complex structure, that may be relatively costly to manufacture and difficult to install in some applications.
Another drawback with many prior art connectors is difficulty, awkwardness, or lack of flexibility in installation. Specifically, many such prior art connectors require specialized installation or mounting structures, and many do not easily permit (or even permit at all) relative lateral movement, or sliding, between two adjacent PC boards. In either case, the installation and removal of interconnected PC boards may require either additional clearance space, or more complex, time-consuming procedures.
Furthermore, many of the prior art connectors do not perform a wiping action against the stationary contacts of the adjacent PC board, thereby allowing debris and oxidation to accumulate, and thus degrading the performance of the connector over time.
Finally, many of the prior art connectors are relatively complex in construction, and therefore relatively expensive to manufacture.
Therefore, it would be a significant advancement in the art to provide a PC board connector that combines a low profile, a high contact element density, good contact element durability, extended contact element travel with a wiping action, simplicity and flexibility in installation, and economy of manufacture.